It's generally assumed that the `extra` field in airflow's Connection model is JSON string. However, it's not, strictly speaking, *required* to be so.
I believe we should require it to be JSON. But I also think we should nudge this a tiny bit further. A python string value such as '"hi"' contains a valid json string "hi". And similarly the string '[0,2,3]' is _also_ a valid string. But this is not at all what is intended for `extra` and, I think for pretty obvious reasons, a bad idea. So I think we should _also_ require that the value for `extra`, if provided, must be json that parses as a python _dict_. So, to summarize, the proposal is, from release 3.0, require that conn `extra` be json (or None) and require that the json (if provided) must parse as a dict. PR to implement deprecation as prescribed by the proposal is here <https://github.com/apache/airflow/pull/21816>. This vote will run until Tuesday at 8am UTC (three full weekdays). Thanks for your consideration.
